The education process has to start with collectors and those who restore when talking about restoration of signs.
Those individuals who are high quality restorers should in some fashion brand their work, like an artist signing a piece of artwork. Collectors should be honest with newcomers to the hobby and pass along their knowledge on how to identify original/resto/repop. To often I've seen collectors attempt to disinform newcomers just so they can beat out that person for an item. Honesty and forthrightness and calling on the carpet those who attempt the opposite should be the norms in any collecting hobby, because if collectors don't police the market no one else will.
There are always going to be three camps of collectors, those who want perfect originals and willingly pay the $$$$ for them, those who want true condition originals, and those who just want to own the piece in nice condition regardless of whether original or restored. Individuals in camp 1, if they are willing to put out the $$$$, should also be educated enough in the hobby to double or triple check for restoration. Individuals in camp 2 shouldn't look down on either of the other 2 camps and should just continue to enjoy the pieces they acquire. Individuals in camp 3 should get to know guys in the other two camps so they don't get burned by restos.
On the restoration issue in general, my opinion is that it's really up to the end buyer and no one else as long as the piece is represented as repaired/restored and priced accordingly. An extremely rare piece (few known) in a condition of 6 (out of 10) can be restored, it just makes sense as the enjoyment of such a rare piece is heightened for both the collector and those who get to see such a sign. For 1 of a kind pieces, if the overall impact of the piece is greatly affected then sympathetic restoration is acceptable, but if restoration isn't going to add aesthetic or preservative value then there isn't really a reason to do it.
If the Mona Lisa were to develop a rip would you not repair it? Would you rather risk the total loss of the piece? Of course not. That's why there are people around the world whose business it is to preserve the pieces of history mankind has left behind. It's no different in the sign collecting world, the idea should be to preserve the history enough without damaging it's authenticity.
I personally have a two piece sign that I would love to see restored because one of the two is far better and repairing the lesser of the two sympathetically would restore the aesthetic appeal. And this is a one of a kind sign, and I believe a full restoration would be far better than a partial one, both aesthetically and value wise.